A number of center-pull dispensers exist in the prior art for dispensing paper toweling and the like from the center of a coreless roll through a nozzle having an opening through which the sheet material passes. Assuming that the individual sheets of toweling or the like are connected by perforated lines, as is common, the nozzle or other element defining an opening through which the sheet material is passed will resist pulling of the sheet material by the user, thus breaking an individual sheet from the remaining web along the perforated lines interconnecting same.
It is quite common to utilize center-pull nozzles which have a cone-like or funnel-shaped configuration. For example, U.S. Pat. No. 4,905,868, issued Mar. 6, 1990, discloses a paper towel dispenser employing a conical funnel having an exit hole smaller than the entrance hole thereof which provides an exit for paper towels being dispensed. The entrance opening and exit opening of the conical funnel are dimensioned such that a first paper towel will separate from a following paper towel along the perforation boundary therebetween when a leading portion of the following paper towel exits from the exit opening of the funnel.
U.S. Pat. No. 5,310,083, issued May 10, 1994, discloses a dispenser nozzle having interconnecting portions, one of which has a truncated cone-like configuration and the other of which has a cylindrical configuration. The portion of the nozzle having the cylindrical configuration is located at the exit opening of the nozzle to provide increased contact area for sheets passing therethrough to reduce wear and extend the life of the nozzle.
Other patents disclosing center-pull nozzles believed to be representative of the current state of the art in the field are as follows: U.S. Pat. No. 5,715,971, issued Feb. 10, 1998, U.S. Pat. No. 5,141,171, issued Aug. 25, 1992, U.S. Pat. No. 5,246,137, issued Sep. 21, 1993, U.S. Pat. No. 5,765,718, issued Jun. 16, 1998, and U.S. Pat. No. 5,749,492, issued May 12, 1998. The patents just noted relate to various approaches for dispensing towels and other sheets from a supply thereof by pulling the sheets through a restricted opening to detach one sheet from another.
Because of the relatively small exit openings employed and required to provide the desired sheet separation, known center-pull dispenser nozzles typically cause considerable wrinkling and crumpling of the sheet material as it exits, resulting in an unsightly sheet being presented to the consumer. Furthermore, some prior art nozzle constructions are not always reliable, it not being uncommon that paper toweling and the like is not always torn along the perforation lines of the web material.
In prior art center pull nozzle constructions the size of the outlet opening must be very precise and accurate. Opening size in such nozzle constructions must be precisely matched to the physical characteristics of the paper or other sheet material passing therethrough, such physical characteristics including thickness, perforation spacing, paper basis weight, etc. If the outlet size varies, for example due to wear during dispenser use, the paper or other sheet material will not dispense properly.